There were 110 registered for the workshop, and I assume that there were around 95 really present at the workshop (at least one of the three days). The participation list was impressive and the most important researchers in the field of user innovation where there: Eric von Hippel (MIT), Joel West (San Jose State), Frank Piller (RWTH Aachen), Nikolaus Franke (WU Vienna), Georg von Krogh (ETH Zürich), Cornelius Herstatt (TUHH) and a lot of other professors, post-docs, and PhD students.
As already Joel West mentioned, Eric von Hippel seems to be the godfather of the user innovation research community. And this is not only Joel's or my opinion - many other participants think the same. In most of the presentations, but also in the pauses between, the presenters closely watched the reaction of Eric and waited for his approval to their work.
Unfortunately there was only one session on Friday, the rest of the time was centered around eating (cake + lasagna) and networking. What I really liked was the very open discussion on what to improve in the next years. The organizers (mainly von Hippel) agreed that it would be useful to integrate an extra feedback session for ongoing projects and to keep the workshop length of three days (maybe three full days, but definitely not compress the workshop into two days).
After the workshop was held in Vienna (2003), Munich (2004, 2006), MIT (2005), Copenhagen (2007), Harvard (2008) and Hamburg (2009) it is planned to go to MIT again for the eight UOI in 2010 and to Vienna in 2011. Eric von Hippel (as one of the organizers) said, that the workshop will be held just before (or after) the Academy of Management in Montreal.
I'm definitely looking forward to meet the community of researchers again in Boston. But until then, I hope that we can establish an online community to bring the researchers more closely together - not only once a year.
(I will post more about the workshop presentations soon)